Featured Research

from universities, journals, and other organizations

New LED streetlight design curbs light pollution

Date:
April 24, 2013
Source:
The Optical Society
Summary:
Recent innovations in light emitting diodes (LEDs) have improved the energy efficiency of streetlights, but, until now, their glow still wastefully radiated beyond the intended area. A team of researchers has developed a new lighting system design that harnesses high-efficiency LEDs and ensures they shine only where they're needed, sparing surrounding homes and the evening sky from unwanted illumination.

Schematic of the new street lamp.
Credit: Optics Express

Streetlights illuminate the night, shining upon roadways and sidewalks across the world, but these ubiquitous elements of the urban environment are notoriously inefficient and major contributors to light pollution that washes out the night sky. Recent innovations in light emitting diodes (LEDs) have improved the energy efficiency of streetlights, but, until now, their glow still wastefully radiated beyond the intended area. A team of researchers from Taiwan and Mexico has developed a new lighting system design that harnesses high-efficiency LEDs and ensures they shine only where they're needed, sparing surrounding homes and the evening sky from unwanted illumination.

Related Articles


The team reported their findings today in the Optical Society's (OSA) open-access journal Optics Express.

A unique feature of the new LED system is its adaptability to different street lamp layouts, "to all kinds of streets and roads, providing a uniform illumination with high energy efficiency," says co-author Ching-Cherng Sun of National Central University in Taiwan. For example, some modern lamps that line a thoroughfare or suburban sidewalk lean into the middle of the road, lighting the street from above. But more often, lamps are posted to one side of a street, or alternating in a "zig-zag" pattern from one side to the other -- a layout that may be more efficient for roads with high traffic flow. The new design provides flexibility to be used for different illumination requests while maintaining a high efficiency, Sun says.

The proposed lamp is based on a novel three-part lighting fixture. The first part contains a cluster of LEDs, each of which is fitted with a special lens, called a Total Internal Reflection (TIR) lens, that focuses the light so the rays are parallel to one another instead of intersecting -- a process called collimation. These lens-covered LEDs are mounted inside a reflecting cavity, which "recycles" the light and ensures that as much of it as possible is used to illuminate the target. Finally, as the light leaves the lamp it passes through a diffuser or filter that cuts down on unwanted glare. The combination of collimation and filtering also allows researchers to control the beam's shape: the present design yields a rectangular light pattern ideally suited for street lighting, the researchers say.

The team tested their design's performance by analyzing how little the beam would spread as it hit its target -- a road or sidewalk 10 meters or more away from the source of the light. They quantified the lamp's performance using something called optical utilization factor (OUF), a number that describes the relationship between the flow rate of light at the target and the flow rate of light coming directly out of the LEDs. Higher OUF indicates better performance. Simulations show that the new design achieves an OUF of 51 to 81 percent, greatly outperforming a recent "excellent" design that reached 45 percent. Furthermore, the proposed streetlamp meets high expectations for power and brightness. And light pollution is also significantly reduced: for conventional street lamps, up to a fifth of their total energy is directed horizontally or upward into the sky. The best LED streetlamps reduce this to a tenth of their total energy. In the new model, just 2 percent of the lamp's total energy would contribute to light pollution.

In addition to cutting light pollution and glare, the new model could also save energy. "A general LED street light could reduce power consumption by 40 to 60 percent," Sun says; the increased efficiency of the proposed design would likely save an additional 10 to 50 percent. Furthermore, he adds, the module would be simple to fabricate, since it comprises just four parts, including a type of LED bulb commonly used in the lighting industry.

Sun's team expects to finish a prototype of their design in the next 3 to 6 months, and to begin practical installations of the new street lamp as early as next year.


Story Source:

The above story is based on materials provided by The Optical Society. Note: Materials may be edited for content and length.


Journal Reference:

  1. Xuan-Hao Lee, Ivan Moreno, Ching-Cherng Sun. High-performance LED street lighting using microlens arrays. Optics Express, 2013; 21 (9): 10612 DOI: 10.1364/OE.21.010612

Cite This Page:

The Optical Society. "New LED streetlight design curbs light pollution." ScienceDaily. ScienceDaily, 24 April 2013. <www.sciencedaily.com/releases/2013/04/130424103130.htm>.
The Optical Society. (2013, April 24). New LED streetlight design curbs light pollution. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2013/04/130424103130.htm
The Optical Society. "New LED streetlight design curbs light pollution." ScienceDaily. www.sciencedaily.com/releases/2013/04/130424103130.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Sony Hopes To Make Any Glasses 'Smart'

How Sony Hopes To Make Any Glasses 'Smart'

Newsy (Dec. 17, 2014) Sony's glasses module attaches to the temples of various eye- and sunglasses to add a display and wireless connectivity. Video provided by Newsy
Powered by NewsLook.com
Los Angeles Police To Receive 7,000 Body Cameras

Los Angeles Police To Receive 7,000 Body Cameras

Newsy (Dec. 17, 2014) Los Angeles Mayor Eric Garcetti announced the cameras will be distributed starting Jan. 1. Video provided by Newsy
Powered by NewsLook.com
Jaguar Unveils 360 Virtual Windshield Making Car Pillars Appear Transparent

Jaguar Unveils 360 Virtual Windshield Making Car Pillars Appear Transparent

Buzz60 (Dec. 17, 2014) Jaguar unveils a virtual 360 degree windshield that may be the most futuristic automotive development yet. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Researchers Bring Player Pianos Back to Life

Researchers Bring Player Pianos Back to Life

AP (Dec. 17, 2014) Stanford University wants to unlock the secrets of the player piano. Researchers are restoring and studying self-playing pianos and the music rolls that recorded major composers performing their own work. (Dec. 17) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins